A resistor is an electronic device that typically has symmetric current-voltage (I-V) characteristics with respect to the polarity of the applied voltage. Existing thin-film non-linear resistors, however, suffer from a lack of I-V symmetry with respect to the polarity of the applied voltage. This lack of symmetry greatly limits the use of such non-linear resistors in a large variety of applications, including signal control for use in liquid crystal or organic light emitting diode display backplanes and electro-magnetic sensor arrays, for example. Thus, it would be an important advance in the art to provide thin-film non-linear resistors that exhibit I-V symmetry with respect to the polarity of the applied voltage.